Shorter Vector Length Research Articles

FATE: A Flexible FPGA-Based Automatic Test Equipment for Digital ICs

The limits of chip technology are constantly being pushed with the continuous development of integrated circuit manufacturing processes and equipment. Currently, chips contain several billion, and even tens of billions, of transistors, making chip testing increasingly challenging. The verification of very large-scale integrated circuits (VLSI) requires testing on specialized automatic test equipment (ATE), but their cost and size significantly limit their applicability. The current FPGA-based ATE is limited in its scalability and support for few test channels and short test vector lengths. As a result, it is only suitable for testing specific chips in small-scale circuits and cannot be used to test VLSI. This paper proposes a low-cost hardware and software solution for testing digital integrated circuits based on design for testability (DFT) on chips, which enables the functional and performance test of the chip. The solution proposed can effectively use the resources within the FPGA to provide additional test channels. Furthermore, the round-robin data transmission mode can also support test vectors of any length and it can satisfy different types of chip test projects through the dynamic configuration of each test channel. The experiment successfully tested a digital signal processor (DSP) chip with 72 scan test pins (theoretically supporting 160 test pins). Compared to our previous work, the work in this paper increases the number of test channels by four times while reducing resource utilization per channel by 37.5%, demonstrating good scalability and versatility.

Association of Bioimpedance Parameters with Increases in Blood Pressure during Hemodialysis.

Intradialytic hypertension, defined as an increase in BP from pre- to post-hemodialysis (HD), affects 5%-15% of patients receiving maintenance HD and is associated with cardiovascular and all-cause mortality. Hypervolemia is believed to be a major etiological factor, yet the association of more objective biomarkers of volume status with intradialytic hypertension is not well described. In a post hoc analysis of the Frequent Hemodialysis Network Daily Trial ( n =234), using data from baseline, 1-, 4-, and 12-month visits ( n =800), we used random-effects regression to assess the association of bioimpedance estimates of volume (vector length) with post-HD systolic BP (continuous) and any increase in systolic BP (categorical) from pre- to post-HD. We adjusted models for randomized group; age; sex; self-reported race; Quételet (body mass) index; vascular access; HD vintage; hypertension; history of heart failure; diabetes; residual kidney function (urea clearance); pre-HD systolic BP; ultrafiltration rate; serum-dialysate sodium gradient; and baseline values of hemoglobin, phosphate, and equilibrated Kt/V urea. The mean age of participants was 50±14 years, 39% were female, and 43% were Black. In adjusted models, shorter vector length (per 50 Ω/m) was associated with higher post-HD systolic BP (2.9 mm Hg; 95% confidence interval [CI], 1.6 to 4.3) and higher odds of intradialytic hypertension (odds ratio 1.66; 95% CI, 1.07 to 2.55). Similar patterns of association were noted with a more stringent definition of intradialytic hypertension (>10 mm Hg increase from pre- to post-HD systolic BP), where shorter vector length (per 50 Ω/m) was associated with a higher odds of intradialytic hypertension (odds ratio 2.17; 95% CI, 0.88 to 5.36). Shorter vector length, a bioimpedance-derived proxy of hypervolemia, was independently associated with higher post-HD systolic BP and risk of intradialytic hypertension.

Mitigating inherent micro-cracking in laser additively manufactured RENÉ 108 thin-wall components

Thin-wall components made of a hard-to-weld Ni-based superalloy, RENÉ 108, are fabricated using laser powder bed fusion. Thirty-two parts, including ten different scan strategies and four different wall thicknesses between 0.25 mm and 1.00 mm, are studied and compared with the conventional continuous 67° scan rotation strategy. Microstructure characterization shows micro-cracks aligned with the build direction and melt-pool boundaries. All micro-cracks exhibit inter-dendritic morphologies in the vicinity of the cracked boundaries, suggesting a solidification cracking mechanism. Thicker parts and long vector length are more susceptible to micro-cracking due to earlier transition to positive stress triaxiality states demonstrated through finite element modeling.​ Parts are processed with alternating and continuous inter-layer scan rotation strategies. Scan rotations reduce micro-cracking propensities by 12%–62% compared to zero scan rotations due to more homogeneous stress distribution during build progression. Furthermore, alternating long vector lengths create 100%–230% more micro-cracks than alternating short vector lengths, which are more beneficial than the 67° continuous rotation strategy due to reduced in-process stresses. Shorter vector lengths with interlayer scan rotations are optimal for micro-crack mitigation.

Performance and power consumption analysis of Arm Scalable Vector Extension

Modern CPUs not only have multiple cores but also support wide single instruction multiple data (SIMD). This trend is expected to grow in the future. In this paper, we examine the effect of the vector length and the number of out-of-order resources on the performance and the power consumption of programs having multiple vector lengths using the Arm Scalable Vector Extension. Based on the performed evaluation, we conclude that using a longer vector length with multicycle vector units leads to up to approximately 30% improvement in performance and 21% decrease in power consumption than when using a shorter vector length.

‘Unit cell’ type scan strategies for powder bed fusion: The Hilbert fractal

Abstract In this study, the melt pool (MP) morphology evolution (solidification) in a Hilbert fractal pattern for the Powder-Bed Fusion Additive Manufacturing (PBF-AM) of Alloy 718 is examined by devising a 'Unit Cell' Methodology (UCM). Since scan strategies are becoming an increasingly important method for managing morphological, microstructural phenomena, and thermally induced stresses, new scan strategies are a requirement. The methodology described here involves defining a 'unit cell' from the larger (higher-order) Hilbert fractal curve and then printing the constitutive lines (vectors) of the 'unit Hilbert cell' and visualising its morphological evolution over a single layer. Process parameters (line length of the 'unit cell,' laser power, and laser speed) variations are performed to analyse its effects on the morphology of the 'unit Hilbert cell' (single layer). The higher-order Hilbert fractal curve is then demonstrated in stages to explain the morphological evolution. The observed coalesced MP propagates over the surface in the larger (higher-order) Hilbert fractal curve, according to the position of the 'unit cells' in the Hilbert fractal curve. The flow of a coalesced MP in PBF-AM using the short vector lengths at a lower linear energy density and three times the width of parallel-line single-track MPs is demonstrated for the first time with the Hilbert fractal. Process parameter variation on the 'unit Hilbert cell' results in MP morphology (dimensions and shape) changes. These variations help to choose the required coalesced MP dimensions in the higher-order Hilbert fractal and ensure good hatching with the adjacent 'unit cell' MPs as it propagates. The proposed methodology could be expanded to allow an understanding of the morphology evolution of other fractal curves in the PBF-AM process.

Densification, mechanical behaviors, and machining characteristics of 316L stainless steel in hybrid additive/subtractive manufacturing

Directed energy deposition (DED) is capable of manufacturing high-density and complex metal components, whereas traditional machining methods are limited in these regards. Nevertheless, the fabrication of parts with DED that have accurate dimensions and geometries as well as acceptable surface states is a concern, as these factors are inferior to those of traditionally machined components. Therefore, the application of parts fabricated with DED is restricted. Thus, the hybrid additive/subtractive manufacturing (HASM) method has been exploited to comprehensively utilize the advantages of both. In this paper, the HASM method was used to fabricate bulk parts with four different scanning strategies (alternating the orientation of subsequent layers by 0°, 45°, and 90° and island scanning are referred to as an X-scan, a Rot-scan, an XY-scan, and an Island-scan, respectively) followed by subtractive milling to gain a smooth surface with a determined thickness for the next scanning and deposition period until the parts were completely finished. The influence of the scanning strategy on the densification level and mechanical behavior of the specimens fabricated with HASM was studied. The results show that the specimens fabricated with the 7 × 7 mm2 island scan with short scan vector lengths showed a higher densification than the specimens fabricated using long scan vector lengths (the three methods mentioned above). Finally, to obtain a fine surface finish, the influence of the feed per tooth (fz) on the surface quality of a 316L stainless steel during the milling process that occurs during the HASM process was also investigated. The result shows a fz of 0.25 mm yielding the minimum surface roughness value among the samples observed herein, which implies that the surface quality was better than that of the other studied conditions.

Using bioimpedance analysis to assess intensive care unit patients with sepsis in the post-resuscitation period: a prospective multicentre observational study.

Clinicians lack well-validated, non-invasive, objective tools to guide volume management in the post-resuscitative period. Bioimpedance analysis (BIA) represents a novel method for guiding fluid management. We studied the relationship of BIA vector length (VL), an indicator of volume status, to the need for mechanical ventilation in patients with sepsis. This is a multicentre prospective observational study at four Canadian ICUs. We examined adult patients admitted to the ICU within 72 hr of a sepsis diagnosis. Patients underwent daily BIA measurements for 30 days, until discharge from the ICU, or until death. Our primary outcome was the ongoing need for invasive mechanical ventilation, and we examined the association with VL using a generalized estimating equation. Our secondary analyses were targeted to determine an association between VL and other measures of volume status and acute kidney injury (AKI). We enrolled 159 patients from four centres over 27 months. The mean (standard deviation [SD]) age was 64 (15) yr with a mean (SD) APACHE (acute physiology, age, chronic health evaluation) II score of 25 (10); 57% (n = 91) were male. A 50-unit (ohm·m) increase in VL over any time period was associated with a 30% decrease in the probability of requiring invasive mechanical ventilation (P < 0.03). Volume expansion, indicated by a shorter VL, correlated with higher edema scores (r = - 0.31; P < 0.001) and higher net 24-hr fluid balance (r = - 0.27, P < 0.001). Patients with AKI had a shorter overall VL (r = - 0.23; P = 0.003). An increase in VL over time is associated with a decrease in probability of requiring invasive mechanical ventilation. Vector length correlates with other commonly used volume assessment methods in post-resuscitation patients with sepsis.

Genotype X environment Interaction and Stability of Oil Content of Sesame (Sesamum indicum L.) Genotypes in Northern Ethiopia

The experiment for oil content analysis was conducted for two growing seasons under rainfed condition (2012-2013) in Humera and Dansha, and in a single year (2013 cropping season) in Sheraro (comprising a total of five environments). The experiment comprised of 13 sesame genotypes, laid out in a randomized complete block design of three replications with the objective of determining the magnitude of Genotype x Environment Interaction (GEI)and oil content. here was highly significant (p0.01) oil content variation based on genotypes, environments and GEI resulting 26%, 42.7 % and 30.9% of the total sum of squares for the oil content variation respectively. The mean of the oil content was 53.9%, with genotypes G4 and G11 with the highest oil content (55.1 %) each, and G8 with the lowest oil content (51.4 %). G4 was the exceptional genotype with the highest oil content (55.1 %) and oil yield (512.9 kg/ha). Based on the Environmental Index (EI) analysis, Environments E4 and E5 were the favourable environments, while E1, E2 and E3 were unfavourable environments for sesame oil production. According to the AMMI1(Additive main effects and multiplicative interaction) bi-plot, Genotypes G4, G13 and G10 with oil the content of 55.1%, 54.7 and 54.2 respectively, were stable genotypes. On the other hand, genotypes G2, G8, G9, G3 and G1 were unstable genotypes in most of the environments. The AMMI 2 bi-plot showed that, genotypes G2, G3 and G9, with long vector length, were specifically adaptable genotypes and genotypes G10, G12, G4 and G7 with shorter vector length were widely adaptable in most of the environments for their oil content. Oil content of sesame varies highly both across years and locations.

Applying circular statistics can cause artefacts in the calculation of vector coding variability: A bivariate solution

BackgroundCoordination variability is thought to provide meaningful insights into motor learning, skill level and injury prevention. Current analytical techniques, based on vector coding (VC) methods, use calculations from circular statistics. However a statistical artefact associated with the application of circular statistics may artificially increase the estimated coordination variability, especially when VC vectors are short. Research questionAre two popular methods for calculating vector coding coordination variability susceptible to contamination by statistical artefacts and if so, how can coordination variability be calculated without statistical artefact? MethodsA combination of simulated and experimental data was used to prove the existence of the statistical artefact and to understand the extent to which it may affect experimental running gait data, respectively. An alternative approach that uses ellipse area as a bivariate measure of variability was proposed, applied to the same dataset, and compared to two popular methods of coordination variability analysis. ResultsThe simulated data showed the existence of a statistical artefact, which was greater for shorter VC vector lengths in coordination variability measures that used circular statistics. The statistical artefact typically manifests itself as inflated peaks in the coordination variability trace. The experimental data also indicated that short vector lengths are prevalent in running gait. The Ellipse Area Method of coordination variability was not affected by the VC vector length. SignificanceResearchers using current VC variability measures should be particularly aware of the possible effect of the statistical artefact on their data, which is most likely to occur when vector lengths are short. The novel approach we have suggested for calculating VC coordination variability may provide the foundation for future research into vector coding coordination variability.

Bioelectrical Impedance Analysis Measures and Clinical Outcomes in CKD

Bioelectrical impedance analysis (BIA) provides a noninvasive assessment of body composition. BIA measures of cell integrity (phase angle) and hydration (vector length) have been associated with mortality among patients receiving dialysis. Whether these measures are associated with clinical outcomes in patients with chronic kidney disease (CKD) is unknown. Observational study. We studied 3,751 participants with CKD in the prospective multicenter Chronic Renal Insufficiency Cohort (CRIC) who had baseline single-frequency BIA performed. Predictors included phase angle and vector length, which were calculated from measurements of resistance and reactance from BIA. We ranked phase angle and vector length into quartiles and compared the 2 narrower quartiles of phase angle and shorter quartiles of vector length with the 2 upper quartiles. Mortality, heart failure, atherosclerotic cardiovascular disease, and progression of CKD (30% decline in estimated glomerular filtration rate or end-stage kidney disease). We tested associations of phase angle and vector length with risks for mortality and progression of CKD using Cox proportional hazard models and the association with heart failure and atherosclerotic cardiovascular disease using Fine and Gray models. All models were adjusted for demographics, comorbidconditions, and kidney function. Mean phase angle and vector length were 6.6°±1.8° and 470 ± 96 Ω/m, respectively. Relative to phase angle≥ 6.40o, narrower phase angle (<5.59o) was significantly associated with mortality (HR, 1.31; 95% CI, 1.09-1.58). Relative to vector length≥ 459 Ω/m, shorter vector length (<401 Ω/m) was significantly associated with heart failure (HR, 1.28; 95% CI, 1.01-1.61). Neither measure was associated with atherosclerotic cardiovascular disease or a composite renal end point. Observational study. Adjusted for key confounders, BIA-derived measures of cellular integrity and tissue hydration were significantly associated with death and incident heart failure, respectively.

Effects of motion and configural complexity on color transparency perception

We tested whether motion and configural complexity affect perceived transparency. A series of five coherent chromatic transformations in color space was applied across a figure: translation, convergence, shear, divergence and rotation. The stimuli consisted of a bipartite or a checkerboard configuration (10 x 10 degrees), with a central static or moving overlay (5 x 5 degrees). Three different luminance conditions (the plane of chromatic transformation oriented toward higher, lower, or equal luminances) were also tested for each of three modulation depths. For each stimulus, the observer judged whether the overlay appeared transparent or not. The main results indicated an interaction between the type of chromatic transformation and stimulus motion and complexity. For example, convergences are judged to appear transparent significantly more often when motion is added for bipartite configurations, or when they are generated in a checkerboard configuration. Surprisingly, shears that have been reported to appear opaque, are more frequently reported to appear transparent with short vector lengths and when combined with motion. Other transformations are also affected by motion, although the effectiveness of figural complexity on transparency seems to depend on both the type of color shifts and the presence of motion. The results indicate that adding motion and stimulus complexity are not necessarily neutral with respect to the chromatic shifts evoking transparency. Thus, studies that have used motion to enhance transparency may yield different results about the color shifts supporting transparency perception from those that did not. The same might be supposed for stimulus complexity under some conditions.

An analysis of clock-shift experiments: is scatter increased and deflection reduced in clock-shifted homing pigeons?

Clock-shifting (altering the phase of the internal clock) in homing pigeons leads to a deflection in the vanishing bearing of the clock-shifted group relative to controls. However, two unexplained phenomena are common in clock-shift experiments: the vanishing bearings of the clock-shifted group are often more scattered (with a shorter vector length) than those of the control group, and the deflection of the mean bearing of the clock-shifted group from that of the controls is often smaller than expected theoretically. Here, an analysis of 55 clock-shift experiments performed in four countries over 21 years is reported. The bearings of the clock-shifted groups were significantly more scattered than those of controls and less deflected than expected, but these effects were not significantly different at familiar and unfamiliar sites. The possible causes of the effects are discussed and evaluated with reference to this analysis and other experiments. The most likely causes appear to be conflict between the directions indicated by the sun compass and either unshifted familiar visual landmarks (at familiar sites only) or the unshifted magnetic compass (possible at both familiar and unfamiliar sites).

Implementation and performance issues of a massively parallel atmospheric model

We present implementation and performance issues of a data parallel version of the National Center for Atmospheric Research (NCAR) Community Climate Model (CCM2). We describe automatic conversion tools used to aid in converting a production code written for a traditional vector architecture to data parallel code suitable for the Thinking Machines Corporation CM-5. Also, we describe the 3-D transposition method used to parallelize the spherical harmonic transforms in CCM2. This method employs dynamic data mapping techniques to improve data locality and parallel efficiency of these computations. We present performance data for the 3-D transposition method on the CM-5 for machine size up to 512 processors. We conclude that the parallel performance of the 3-D transposition method is adversely affected on the CM-5 by short vector lengths and array padding. We also find that the CM-5 spherical harmonic transforms spend about 70% of their execution time in communication. We detail a transposition-based data parallel implementation of the semi-Lagrangian Transport (SLT) algorithm used in CCM2. We analyze two approaches to parallelizing the SLT, called the departure point and arrival point based methods. We develop a performance model for choosing between these methods. We present SLT performance data which shows that the localized horizontal interpolation in the SLT takes 70% of the time, while the data remapping itself only require approximately 16%. We discuss the importance of scalable I/O to CCM2, and present the I/O rates measured on the CM-5. We compare the performance of the data parallel version of CCM2 on a 32-processor CM-5 with the optimized vector code running on a single processor Cray Y-MP. We show that the CM-5 code is 75% faster. We also give the overall performance of CCM2 running at higher resolutions on different numbers of CM-5 processors. We conclude by discussing the significance of these results and their implications for data parallel climate models.

Vectorized poisson solvers for the Navier–Stokes equations

AbstractThe advent of vector and massively parallel computers offers researchers the possibility of enormous gains in execution time for scientific and engineering programs. From the numerical point of view, such programs are frequently based on the inversion of sparse, diagonally banded matrices. Conventional scalar solvers often perform poorly on vector machines due to short effective vector lengths, and thus appropriate methods must be chosen for use with vector machines. In this paper a number of commonly used solvers are tested for the Navier–Stokes equations, in both scalar and vector form, on two vector architecture machines. A new method is presented which performs well in both vector and scalar form on a range of vector architectures.

Queuing Model Analysis of the Fujitsu Vp2000 With Dual Scalar Architecture

A queuing model analysis is given for the performance evaluation of a dual scalar processor (DSP), which is composed of two scalar units and one vector unit. The performance evaluation is for three different processor models with equivalent hardware capacity: homoge neous DSP (DSP1), heterogeneous DSP (DSP2), and multiprocessor (MP), with particular attention given to the case of short vector lengths. It is found that the performance of DSP1 is preferable to that of MP for most actual workloads, and in particular for the work load of the Japan Atomic Energy Research Institute. The effect of the dual scalar capacity, that is, of attach ing a secondary scalar unit, is also investigated. It is shown that the throughput of DSP1 is about 1.8 times that of the uniprocessor, for a vectorization ratio of 90%.